Anthony M. Musolf

REVEL: An Ensemble Method for Predicting the Pathogenicity of Rare Missense Variants

The vast majority of coding variants are rare, and assessment of the contribution of rare variants to complex traits is hampered by low statistical power and limited functional data. Improved methods for predicting the pathogenicity of rare coding variants are needed to facilitate the discovery of disease variants from exome sequencing studies. We developed REVEL (rare exome variant ensemble learner), an ensemble method for predicting the pathogenicity of missense variants on the basis of individual tools: MutPred, FATHMM, VEST, PolyPhen, SIFT, PROVEAN, MutationAssessor, MutationTaster, LRT, GERP, SiPhy, phyloP, and phastCons. REVEL was trained with recently discovered pathogenic and rare neutral missense variants, excluding those previously used to train its constituent tools. When applied to two independent test sets, REVEL had the best overall performance (p < 10-12) as compared to any individual tool and seven ensemble methods: MetaSVM, MetaLR, KGGSeq, Condel, CADD, DANN, and Eigen. Importantly, REVEL also had the best performance for distinguishing pathogenic from rare neutral variants with allele frequencies <0.5%. The area under the receiver operating characteristic curve (AUC) for REVEL was 0.046-0.182 higher in an independent test set of 935 recent SwissVar disease variants and 123,935 putatively neutral exome sequencing variants and 0.027-0.143 higher in an independent test set of 1,953 pathogenic and 2,406 benign variants recently reported in ClinVar than the AUCs for other ensemble methods. We provide pre-computed REVEL scores for all possible human missense variants to facilitate the identification of pathogenic variants in the sea of rare variants discovered as sequencing studies expand in scale.

Familial Lung Cancer: A Brief History from the Earliest Work to the Most Recent Studies.

Lung cancer is the deadliest cancer in the United States, killing roughly one of four cancer patients in 2016. While it is well-established that lung cancer is caused primarily by environmental effects (particularly tobacco smoking), there is evidence for genetic susceptibility. Lung cancer has been shown to aggregate in families, and segregation analyses have hypothesized a major susceptibility locus for the disease. Genetic association studies have provided strong evidence for common risk variants of small-to-moderate effect. Rare and highly penetrant alleles have been identified by linkage studies, including on 6q23–25. Though not common, some germline mutations have also been identified via sequencing studies. Ongoing genomics studies aim to identify additional high penetrance germline susceptibility alleles for this deadly disease.

Caucasian families exhibit significant linkage of Myopia to chromosome 11p

Purpose Myopia is a common visual disorder caused by eye overgrowth, resulting in blurry vision. It affects one in four Americans, and its prevalence is increasing. The genetic mechanisms that underpin myopia are not completely understood. Here, we use genotype data and linkage analyses to identify high-risk genetic loci that are significantly linked to myopia. Methods Individuals from 56 Caucasian families with a history of myopia were genotyped on an exome-based array, and the single nucleotide polymorphism (SNP) data were merged with microsatellite genotype data. Refractive error measures on the samples were converted into binary phenotypes consisting of affected, unaffected, or unknown myopia status. Parametric linkage analyses assuming an autosomal dominant model with 90% penetrance and 10% phenocopy rate were performed. Results Single variant two-point analyses yielded three significantly linked SNPs at 11p14.1 and 11p11.2; a further 45 SNPs at 11p were found to be suggestive. No other chromosome had any significant SNPs or more than seven suggestive linkages. Two of the significant SNPs were located in BBOX1-AS1 and one in the intergenic region between ORA47 and TRIM49B. Collapsed haplotype pattern two-point analysis and multipoint analyses also yielded multiple suggestively linked genes at 11p. Multipoint analysis also identified suggestive evidence of linkage on 20q13. Conclusions We identified three genome-wide significant linked variants on 11p for myopia in Caucasians. Although the novel specific signals still need to be replicated, 11p is a promising region that has been identified by other linkage studies with a number of potentially interesting candidate genes. We hope that the identification of these regions on 11p as potential causal regions for myopia will lead to more focus on these regions and maybe possible replication of our specific linkage peaks in other studies. We further plan targeted sequencing on 11p for our most highly linked families to more clearly understand the source of the linkage in this region.

Parametric Linkage Analysis Identifies Five Novel Genome-Wide Significant Loci for Familial Lung Cancer

Objective: One of four American cancer patients dies of lung cancer. Environmental factors such as tobacco smoking are known to affect lung cancer risk. However, there is a genetic factor to lung cancer risk as well. Here, we perform parametric linkage analysis on family-based genotype data in an effort to find genetic loci linked to the disease. Methods: 197 individuals from families with a high-risk history of lung cancer were recruited and genotyped using an Illumina array. Parametric linkage analyses were performed using an affected-only phenotype model with an autosomal dominant inheritance using a disease allele frequency of 0.01. Three types of analyses were performed: single variant two-point, collapsed haplotype pattern variant two-point, and multipoint analysis. Results: Five novel genome-wide significant loci were identified at 18p11.23, 2p22.2, 14q13.1, 16p13, and 20q13.11. The families most informative for linkage were also determined. Conclusions: The 5 novel signals are good candidate regions, containing genes that have been implicated as having somatic changes in lung cancer or other cancers (though not in germ line cells). Targeted sequencing on the significant loci is planned to determine the causal variants at these loci.

Abstract 4268: Familial lung cancer is significantly linked to cancer-associated genes on five chromosomes

Lung cancer (LC) is the leading cancer killer of Americans; an estimated 158,000 people will die in the U.S. from LC in 2016. While it is well-known that LC risk is affected by the environment, particularly tobacco smoking, there is a substantial genetic risk to LC also. We examined genotype data from Illumina HumanCore-12v1-0 array (297,000 SNPs) on 175 individuals in 25 extended families with a strong history of LC recruited by the Genetic Epidemiology of Lung Cancer Consortium. The purpose of this study is to determine which families are segregating a high-penetrance genetic risk haplotype so that the most informative families can be selected for DNA sequencing studies. Quality control was performed to remove SNPs and individuals with greater than 1% missingness as well as monomorphic SNPs. SNPs with Mendelian errors in more than one family were dropped. Identity-by-descent values were calculated to confirm correct familial relationships; 1 individual was dropped. After quality control we were left with approximately 245,000 SNPs for analysis. We performed three types of parametric linkage analyses using an autosomal dominant model with 40% penetrance in carriers and 1% penetrance in non-carriers. A disease allele frequency of 0.01 was used. Standard single variant two-point analysis between the disease and each marker was performed using TwoPointLods. Multipoint linkage analysis was performed using SimWalk2. We also performed regional-based linkage analyses using SEQLinkage and MERLIN. SEQLinkage builds a multiallelic regional marker (similar to a microsatellite) that corresponds to a gene or a portion of a gene. Two-point linkage analyses were then performed on the regional markers using MERLIN. We identified five loci that were genome-wide significant (HLOD score ≥ 3.3) from the regional-based linkage analyses on 18p11.23 (HLOD = 4.1), 2p22.2 (3.9), 14q13.1 (3.7), 16p13.1 (3.4), and 20q13.11 (3.4). It is particularly exciting that the scores centered on prospective cancer genes. Our highest score was centered on PTPRM, a protein tyrosine phosphatase on chromosome 18 that has been implicated as a LC oncogene. The signal on 20q13 also centered on another protein tyrosine phosphatase (PTPRT) that has been shown to be mutated in LC cells. The source of the signal on 16p13 was RNA binding protein RBFOX1, which has been shown to be deleted in LC cell lines and the source of the signal on 2p22 was LRP1B, a LDL receptor-related protein that is often inactivated in LC cells. The source of the final signal on 14q13 was NPAS3, a transcription factor that is a tumor suppressor in brain tumors. It should be noted that all previous evidence linking these genes to cancer was based on somatic mutations; this is the first time any of these genes has been shown to be significantly linked to germline disease risk in a family-based study. We plan to perform targeted sequencing on the linked regions to elucidate the exact causal variant. Citation Format: Joan E. Bailey-Wilson, Anthony M. Musolf, Claire L. Simpson, Mariza de Andrade, Diptasri Mandal, Colette G. Gaba, Ping Yang, Ming You, Elena Y. Kupert, Marshall W. Anderson, Ann G. Schwartz, Susan M. Pinney, Christopher I. Amos. Familial lung cancer is significantly linked to cancer-associated genes on five chromosomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4268. doi:10.1158/1538-7445.AM2017-4268

Abstract 2542: Chromatin remodeling gene ARID1B is linked to familial lung cancer

Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, LA Several papers have implicated mutations in the AT-rich interactive domain containing protein 1B (ARID1B) in carcinoma formation in multiple tissue types, including the lung. The ARID1B protein functions as part of SWI/SNF, a multi-subunit chromatin remodeling complex that repositions nucleosomes and may act as a tumor suppressor in cancer. ARID1B is located in a region in 6q that was previously shown to have strong evidence of linkage with lung cancer risk. As it is one of the more promising candidates within the target region, this study presents the viability of ARID1B as a candidate gene for familial lung cancer. Here, we chose individuals from families in our previous linkage study that showed the strongest linkage signal on 6q. 75 individuals from 9 families were sequenced for 37Mb of chromosome 6 from 130Mb to 167Mb using Illumina technology and a custom Agilent kit. Genotypes were imported into GoldenHelix SVS 7 for quality control and dropped if read depth < 10, quality score < 10 or a quality score to read depth ratio < 0.5. Variants with more than 1 Mendelian error were dropped. Variants with a single Mendelian inconsistency were dropped only for that family. Two-point parametric linkage analysis at theta = 0 was performed using R and an implementation of the Elston-Stewart algorithm in the paramlink package using a penetrance model of 0.01/0.1/0.1 (dd/Dd/DD) and a disease allele (D) frequency of 0.01. Family 102 showed strong evidence for linkage near ARID1B. The highest LOD score (1.34) out of all sequenced variants was located near this gene in a known conserved intergenic region between ARID1B and NOX3. Four other LOD scores > 0.7 were found in the intergenic region between these two genes. Two are transcription factor binding sites; two are conserved genomic elements. We also observed two linked intronic variants of ARID1B in this family; an enhancer (LOD = 0.89) and a transcribed region (LOD = 0.73). Two other families (47 and 59) displayed evidence of linkage in ARID1B. Here, the interest is not the value of the LOD scores (top scores were 0.64 and 0.54), but the centering of the linked haplotype around the gene. Family 47 has 60 variants with LODs between 0.64 and 0.61; 45 located within ARID1B or known regulatory regions. Family 59 has 61 variants with LODs between 0.54 and 0.51; 29 located within ARID1B or known regulatory regions The variants appear to be spread evenly throughout ARID1B, suggesting the presence of linked haplotypes. Analyses are currently underway to reconstruct possible haplotypes in these families. The results of this study show that variants in the ARID1B gene at least partially account for the linkage signal on 6q in three of the nine most strongly linked families in our cohort and thus we believe that ARID1B is a plausible candidate gene for further studies involving familial lung cancer. Replication studies using 27 new extended families are currently underway to confirm this initial result. Citation Format: Anthony M. Musolf, Claire L. Simpson, Mariza de Andrade, Diptasri Mandal, Colette Gaba, Ping Yang, Ming You, Elena Y. Kupert, Marshall W. Anderson, Ann G. Schwartz, Susan M. Pinney, Christopher I. Amos, Joan E. Bailey-Wilson. Chromatin remodeling gene ARID1B is linked to familial lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2542.